/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.util;

import org.apache.tomcat.util.res.StringManager;

import java.io.Serializable;
import java.util.*;

/**
 * Implementation of <strong>java.util.Map</strong> that includes a
 * <code>locked</code> property.  This class can be used to safely expose
 * Catalina internal parameter map objects to user classes without having
 * to clone them in order to avoid modifications.  When first created, a
 * <code>ParmaeterMap</code> instance is not locked.
 *
 * @param <K> Key type
 * @param <V> Value type
 * @author Craig R. McClanahan
 */
public final class ParameterMap<K, V> implements Map<K, V>, Serializable {

	private static final long serialVersionUID = 2L;
	/**
	 * The string manager for this package.
	 */
	private static final StringManager sm = StringManager.getManager("org.apache.catalina.util");
	private final Map<K, V> delegatedMap;
	private final Map<K, V> unmodifiableDelegatedMap;
	/**
	 * The current lock state of this parameter map.
	 */
	private boolean locked = false;

	/**
	 * Construct a new, empty map with the default initial capacity and
	 * load factor.
	 */
	public ParameterMap() {
		delegatedMap = new LinkedHashMap<K, V>();
		unmodifiableDelegatedMap = Collections.unmodifiableMap(delegatedMap);
	}

	/**
	 * Construct a new, empty map with the specified initial capacity and
	 * default load factor.
	 *
	 * @param initialCapacity The initial capacity of this map
	 */
	public ParameterMap(int initialCapacity) {
		delegatedMap = new LinkedHashMap<K, V>(initialCapacity);
		unmodifiableDelegatedMap = Collections.unmodifiableMap(delegatedMap);
	}

	/**
	 * Construct a new, empty map with the specified initial capacity and
	 * load factor.
	 *
	 * @param initialCapacity The initial capacity of this map
	 * @param loadFactor      The load factor of this map
	 */
	public ParameterMap(int initialCapacity, float loadFactor) {
		delegatedMap = new LinkedHashMap<K, V>(initialCapacity, loadFactor);
		unmodifiableDelegatedMap = Collections.unmodifiableMap(delegatedMap);
	}

	/**
	 * Construct a new map with the same mappings as the given map.
	 *
	 * @param map Map whose contents are duplicated in the new map
	 */
	public ParameterMap(Map<K, V> map) {
		delegatedMap = new LinkedHashMap<K, V>(map);
		unmodifiableDelegatedMap = Collections.unmodifiableMap(delegatedMap);
	}

	/**
	 * Get the locked state of this parameter map.
	 *
	 * @return {@code true} if the Map is locked, otherwise {@code false}
	 */
	public boolean isLocked() {
		return locked;
	}

	/**
	 * Set the locked state of this parameter map.
	 *
	 * @param locked The new locked state
	 */
	public void setLocked(boolean locked) {
		this.locked = locked;
	}

	/**
	 * {@inheritDoc}
	 *
	 * @throws IllegalStateException if this map is currently locked
	 */
	@Override
	public void clear() {
		checkLocked();
		delegatedMap.clear();
	}

	/**
	 * {@inheritDoc}
	 *
	 * @throws IllegalStateException if this map is currently locked
	 */
	@Override
	public V put(K key, V value) {
		checkLocked();
		return delegatedMap.put(key, value);
	}

	/**
	 * {@inheritDoc}
	 *
	 * @throws IllegalStateException if this map is currently locked
	 */
	@Override
	public void putAll(Map<? extends K, ? extends V> map) {
		checkLocked();
		delegatedMap.putAll(map);
	}

	/**
	 * {@inheritDoc}
	 *
	 * @throws IllegalStateException if this map is currently locked
	 */
	@Override
	public V remove(Object key) {
		checkLocked();
		return delegatedMap.remove(key);
	}

	private void checkLocked() {
		if (locked) {
			throw new IllegalStateException(sm.getString("parameterMap.locked"));
		}
	}

	@Override
	public int size() {
		return delegatedMap.size();
	}

	@Override
	public boolean isEmpty() {
		return delegatedMap.isEmpty();
	}

	@Override
	public boolean containsKey(Object key) {
		return delegatedMap.containsKey(key);
	}

	@Override
	public boolean containsValue(Object value) {
		return delegatedMap.containsValue(value);
	}

	@Override
	public V get(Object key) {
		return delegatedMap.get(key);
	}

	/**
	 * {@inheritDoc}
	 * <p>
	 * Returns an <strong>unmodifiable</strong> {@link Set} view of the keys
	 * contained in this map if it is locked.
	 */
	@Override
	public Set<K> keySet() {
		if (locked) {
			return unmodifiableDelegatedMap.keySet();
		}

		return delegatedMap.keySet();
	}

	/**
	 * {@inheritDoc}
	 * <p>
	 * Returns an <strong>unmodifiable</strong> {@link Collection} view of the
	 * values contained in this map if it is locked.
	 */
	@Override
	public Collection<V> values() {
		if (locked) {
			return unmodifiableDelegatedMap.values();
		}

		return delegatedMap.values();
	}

	/**
	 * {@inheritDoc}
	 * <p>
	 * Returns an <strong>unmodifiable</strong> {@link Set} view of the mappings
	 * contained in this map if it is locked.
	 */
	@Override
	public Set<java.util.Map.Entry<K, V>> entrySet() {
		if (locked) {
			return unmodifiableDelegatedMap.entrySet();
		}

		return delegatedMap.entrySet();
	}
}
